We are studying the structure and function of extracellular matrix components. Our data define how the components of skin, cartilage and basement membrane interact with each other to assemble into supramolecular complexes. The basement membrane collagens, proteoglycans, cell attachment proteins and other glycoproteins of the respective tissues bind to each other in a highly specific manner and in precisely defined stoichiometry to form ordered complexes. These interactions define the structure and function of the matrix in tissue morphogenesis, in wound repair and in certain diseases. Various biological activities of neonatal Schwann cells are controlled by basement membrane components. The adhesion and growth of these cells is specifically increased several-fold by laminin and the cells appear more differentiated and elongated. These and other studies on cultured cells indicate that the matrix components regulate tissue formation and repair by controlling which cells can attach and proliferate and direct the development of tissues.